The return of a popular S4C programme will investigate an incident at the heart of a troublesome period in the early 1980s – the burning of holiday homes in North Wales by a campaign group called ‘Wyrion Llywelyn’.

The special mockumentary episode Neb yn Gwybod Dim Byd kicks off the award-winning surreal sketch series on Friday, February 27 at 9.30pm.

The title of the programme refers to a song performed by Bryn Fôn, ‘Mae Rhywun yn Gwybod’ (‘Someone Somehwere Knows’) about the real Welsh arsonist Group, Meibion Glyndŵr.

The early 1980s was a tense period in rural Wales. With the sale of holiday homes increasing, locals Arwel Jones, Malcolm ‘Sosej’ Morris and Emrys Hughes were concerned about the effect of incomers on Welsh-speaking communities.

In a hard-hitting investigation, reporter Angharad Griffiths asks what happened to the patriotic trio and tries to find out whether they were guilty of burning holiday homes in north west Wales.

Aiding the investigation is the hopeless PC Preis, who claims to possess recordings of phone calls made by the three... somewhere.

Others providing evidence include the homeowners affected by the arson attacks and Plismon Puw, one of the first people on the scene to witness the destruction.

Meanwhile, the reporter finds it difficult to focus on the case and other people don’t seem to know much about it either. The cameras follow Arwel, Sosej and Emrys as they reunite for the first time since the attacks, but will there be enough evidence to convict them once and for all?

The rest of the series continues with the popular sketches that have made Dim Byd a household name for alternative comedy in Wales. Old favourites ‘Y Tad Maximillian’ and ‘Lle Goblin’ return in addition to new arrivals the ‘Reservoir Gogs’, a dangerous band of Caernarfon-based gangsters, and an alternative take on classic teenage series ‘Jabas’. The familiar faces of Huw Llywelyn Davies, Hywel Gwynfryn, John Ogwen and Iolo Williams also feature in the new series.

series’ producer, Barry Jones said: “The original intention was to create a sketch show that would attract the attention of younger viewers, as they tend to channel-hop a lot and take in a lot of information. So we decided on a format based on channel hopping!

“We try to include a lot of surreal sketches, some slapstick and others that get the viewer to try to work something out. Every sketch is quite short, so if you don’t like one, there’ll be another just seconds away!”

This is the fourth series of Dim Byd, which began in 2011. It won a BAFTA Cymru award in 2014 for the Best Music and Entertainment programme and Best Children’s programme in 2012.